package thread;
//CountDownLatch
import java.util.Random;
import java.util.concurrent.CountDownLatch;

public class ThreadDemo14 {
    public static void main(String[] args) throws InterruptedException {
        //1.此处构造方法中写10,意思是有十个线程/任务
        CountDownLatch latch = new CountDownLatch(10);
        //创建出10个线程负责下载
        for (int i = 0; i < 10; i++) {
            int id = i;
            Thread t = new Thread(()->{
                Random random = new Random();
                //[0,5)
                int time = (random.nextInt(5)+1)*1000;
                System.out.println("线程"+id+"开始下载");
                try{
                    Thread.sleep(time);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                }
                System.out.println("线程"+id+"结束下载了");
                //2.告知countDownLatch我执行结束了
                latch.countDown();
            });
            t.start();


        }
        //3.通过await操作来等待所有任务结束,也就是countDown被调用10次了
        latch.await();
        System.out.println("所有任务已完成");
    }
}
